Study on Identification of Inductive-Motors Load Partition Based on Coherence

A new inductive motors load equivalence algorithm based on coherence is proposed in this paper. In order to partite motors load rapidly and accurately, fuzzy c-means clustering along with particle swarm optimization (PSO-FCM) algorithm is proposed to identify coherent motors base on its physical essence of fuzziness. The merits of PSO algorithm are independent to initial value and convergent to optimum value rapidly, and the validity function is constructed to assess clustering validity. The test on IEEE 39-Bus System is presented to evaluate the effectiveness of the new algorithm, the membership matrix definite not only coherence group of motors but also correlation value of coherence between motors. The algorithm can be used to partite motor load based on coherency in dynamic equivalence with power system operating on different modes.

Modified Single Phase SRF d-q Theory Based Controller for DVR Mitigating Voltage Sag in Case of Nonlinear Load

This paper mainly concentrates on design of improved controller and its implementation based on single phase synchronous reference frame theory (SRFT) for Dynamic Voltage Restorer (DVR) compensating voltage sag particularly for nonlinear load. In case of single phase distribution line with nonlinear load, the complexity of controller’s design becomes more serious issue. The present single phase and/or three phase theories applicable to DVR shows poor response to restore voltage sag in case of nonlinear load due to presence of harmonics. Hence restoration of voltage sag in single phase nonlinear load connected system has been a serious concern. Therefore, new controller for DVR has been proposed incorporating effective design concept for fundamental component extraction in case of nonlinear load. The single phase SRFT based main controller for DVR works on two separate closed path viz. feed forward path for quick transient response and feedback path for reducing the steady state error. Moreover, pre-sag mitigation strategy of DVR has been adapted through these two aforementioned paths. Complete design of proposed controller is based on phasor analysis. It also consist of proportional integral (PI) controller to reduce the error in the DC-link voltage during compensation time. The controller performance has been verified in MATLAB Simulink for both types (linear and nonlinear) of load. The results obtained indicates that the proposed controller is effective in its performance.

True-Load载荷反求算法研究与应用

利用True-Load软件提供True-Load载荷反求算法,结合有限元技术从应变测量中获得载荷,对天线基座进行了研究.结果表明,如果想要这种方法取得成效,必须具备两个必要条件:有限元模型与试验对象必须具有较高的一致性;由该软件优化出来的应变片贴片点必须与实际的贴片位置保持一致.研究结果为根据应变反求出载荷这种算法的可靠性提供了一些参考价值.

Dynamic Responses of Mobile Offshore Base Connectors

A Mobile Offshore Base (MOB) is a multi-purpose logistics base, which can be stationed in coastal or international waters. In the conceptual design of the MOB, attention should he paid to the dynamic responses of the inter-module connectors because tremendous loads occur in the connectors. In this paper, a study on dynamic responses of the MOB connectors is carried out by use of the Rigid Module Flexible Connector (RMFC) model which assumes that the module stiffness is significantly larger than that of the connector. In the analysis, the connector is modeled as a linear spring, which restricts relative translations but allows for relative rotations of modules. The 3-D source distribution method is adopted to determine the hydrodynamic forces of the modules, and the hydrodynamic interaction between modules is taken into account. The module motions and connector loads for 12 connector stiffness cases in regular and irregular waves are calculated with the multi-rigid-body motion equations. And the calculated results are compared with those from relative references. It is shown that the results obtained by different methods are in good agreement.

SYNCHRONOUS EFFECT OF SLIPPING HEAVY LOADS ON RO-RO SHIP ROLLING IN WAVES

Common effect of wave and slip of internal vehicles will make rolling of the roll-on ship serious. This is one of the important reasons for overturn of ro-ro ships. The multibody system with a floating base is composed of ro-ro ship and slipping vehicles. Takes the rolling angle of the ship and the transverse displacements of the slipping vehicles on desk as freedoms. Making use of the analysis of apparent gravitation and apparent buoyancy, the wave rolling moment is derived. By means of dynamic method of multibody system, dynamic equations of the system are established. Taking a certain channel ferry as an example, a set of numerical calculation have been carried out for rolling response of the multibody system with a floating base of a ro-ro ship and displacements response of the slipping vehicles under common effect of free slipping vehicles and wave, and a conclusion has been drawn that the motion of the numerous free slipping heavy loads will trend to be synchronous under restraining of the side-wall bulkhead with time because of repeated collision.

Lateral load pattern in pushover analysis

The seismic capacity curves of three types of buildings including frame,frame-shear wall and shear wall ob- tained by pushover analysis under different lateral load patterns are compared with those from nonlinear time history analy- sis.Based on the numerical results obtained a two-phase load pattern:an inverted triangle(first mode)load pattern until the base shear force reaches β times its maximum value,V_(max)followed by a(x/H)~α form,here β and α being some coeffi- cients depending on the type of the structures considered,is proposed in the paper,which can provide excellent approxima- tion of the seismic capacity curve for low-to-mid-rise shear type buildings.Furthermore,it is shown both the two-phase load pattern proposed and the invariant uniform pattern can be used for low-to-mid-rise shear-bending type and low-rise bending type of buildings.No suitable load patterns have been found for high-rise buildings.

Value analysis of district heating system with gas-fired peak load boiler in secondary network

In district heating(DH) system with gas-fired peak load regulating boiler in the secondary network,by prolonging run time of base load plants under rated condition,the mean energy efficiency could be increased. The fuels of the system,including coal and gas,would cause different environmental impacts. Meanwhile,the reliability of the heating networks would be changed because the peak load regulating boiler could work as a standby heat source. A model for assessment of heating system was established by value analysis to optimize this kind of system. Energy consumption,greenhouse gas emission,pollution emission and system reliability were selected as functional assessment indexes in the model. Weights of each function were determined by analytical hierarchy process (AHP) and experts consultation. Life cycle cost was used as the cost in the model. A real case as an example was discussed to obtain the optimal base load ratio. The result shows that the optimal base load ratio of the case is 0.77.

面向高比例分布式能源接入的输配网两阶段风险调度研究

随着大量高比例可再生能源接入配电网,潮流呈现双向化,输电网和配电网互联性增加,分散独立的调度影响电网可靠稳定运行水平。面对输网与配网间互济需求增强的现状,提出了面向高比例分布式能源接入的输配电网两阶段风险调度研究。首先以最小运行成本为目标,构建考虑输配电网不同运行风险的日前经济调度模型,在风险限值约束情况下协同优化系统源网荷储多种可调资源;其次构建目标函数为综合风险值最小的日内风险调度模型,计算三类运行风险指标值,对日前可调控资源进行出力计划调整;最后通过改进的粒子群算例求解模型,证明了该模型可使输配电网间交互协调,协同优化运行成本与运行风险,验证了所提两阶段风险调度模型的有效性和优越性。

Performance Analysis of an Enhanced Load Balancing Scheme for Wireless Sensor Networks

Research interest in sensor networks routing largely considers minimization of energy consumption as a major performance criterion to provide maximum sensors network lifetime. When considering energy conservation, routing protocols should also be designed to achieve fault tolerance in communications. Moreover, due to dynamic topology and random deployment, incorporating reliability into protocols for WSNs is very important. Hence, we propose an improved scalable clustering-based load balancing scheme (SCLB) in this paper. In SCLB scheme, scalability is achieved by dividing the network into overlapping multihop clusters each with its own cluster head node. Simulation results show that the proposed scheme achieves longer network lifetime with desirable reliability at the initial state compare with the existing multihop load balancing approach.

质量体积双约束下车辆装载与配送路径联合优化研究

目的针对质量与体积共同限制的配送路径问题,综合考虑订单不可拆分、货物的体积等约束,构建包含路径最短和装载率最高双目标的车辆装载与配送路径联合优化模型。方法在车辆路径优化模型的求解方面,首先利用聚类算法对配送区域进行划分,然后通过车辆的载质量判断是否能进行站点货物的配送,最后利用遗传算法求得最优路径。在三维装载模型的求解上使用贪心算法和基于块的启发式算法,解决了货物的装箱问题。结果基于某公司具体实例对模型与算法的可行性进行了验证,优化后配送的车辆减少了1辆,配送距离减少了154.247 km,平均装载率达到了93.89%,节省了企业的配送成本。结论所构建的模型以及求解的算法可以提高装载率和配送效率,为解决车辆装载与配送路径联合优化问题提供理论依据。

非均匀质量高层结构风振基底剪力计算研究

针对荷载规范中顺风向等效静力风荷载计算公式难以准确评估非均匀质量的高层结构基底剪力,提出竖向空间相关性折算系数η_(z)和质量转换系数m_(cn),分别考虑了多自由度体系与无限自由度体系两者竖向空间相关性的差异和质量非均匀分布对基底剪力的影响,对规范方法进行改进,结合两个算例进行验证;同时分析振型系数、建筑高度和地貌类型对η_(z)的影响.研究表明:竖向空间相关性折算系数η_(z)能反映多自由度体系与无限自由度体系两者竖向空间相关性的差异对基底剪力的影响,算例考虑该影响与否的误差分别为1.2%和2.8%;质量转换系数m_(cn)能反映质量非均匀分布对基底剪力的影响,算例考虑该影响与否的误差为小于5%和等于28.5%;两系数结合规范方法可准确计算非均匀质量高层结构风振基底剪力.η_(z)随着地面粗糙度增加和建筑高度增加而增大,随着指数型振型系数的指数增大而减小;η_(z)参数分析的最小值为0.922,误差可达5%以上;当设计不考虑多自由度体系和无限自由度体系两者竖向空间相关性的差异对基底剪力的影响时,按多自由度体系计算是偏于安全的.针对不同工程,质量转换系数m_(cn)取值需根据具体楼层质量与振型系数计算确定.

Autonomous and Incidental Learning of Vocabulary Through Task-based Language Teaching

This study mainly discussed the effects of three tasks of translating authentic business report on L2 vocabulary learning.160 students were chosen from different majors by a pre-task proficiency test.The findings revealed that task 3 was the optimum task in vo-cabulary gain and direct vocabulary learning had a more facilitated power than incidental vocabulary learning in this translation task forthe learners with the lowest level of vocabulary.This study also suggested that the caution of need and evaluation needed to be adjustedand paid for the learners with the lowest vocabulary level.

Principal axes of M-DOF structures PartⅡ:Dynamic loading

This paper is the second in a two-part series that discusses the principal axes of M-DOF structures subjected to static and dynamic loads.The primary purpose of this series is to understand the magnitude of the dynamie response of structures to enable better design of structures and response modification devices/systems.Under idealized design condi- tions,the structural responses are obtained by using single directinn input ground motions in the direction of the intended response modification devices/systems,and by assuming that the responses of the structure is deconpleable in three mutual- ly perpendicular directions.This standard practice has been applied to both new and retrofitted structures using various seis- mic protective systems.Very limited information is available on the effects of neglecting the impact of directional couplings (cross effects of which torsion is a component)of the dynamic response of structures.In order to quantify such effects,it is necessary to examine the principal axes of structures under both static and dynamic loading.In this twn-part series,the first paper is concerned with static loading,which provides definitions and fundamental formulations,with the conclusion that cross effects of a statically loaded M-DOF structure resulting from the lack of principal axes are of insignificant magnitude. However,under dynamic or earthquake loading,a relatively small amount of energy transferred across perpendicular direc- tions is accumulated,which may result in significant enlargement of the structural response.This paper deals with a formu- lation to define the principal axes of M-DOF structures under dynamic loading and develops quantitative measures to identify cross effects resuhing from the non-existence of principal axes.

Finite element analysis of γ'-phase raft mechanism in Ni-based single crystal superalloy

The finite element method was applied to study the mechanics of rafting ofγ' precipitates in a single crystal Ni-based superalloy with the [001] orientation. The results show that the creep and rafting are closely related with the stress and strain energy density distributions in the matrix channels. The application of an external stress leads to differential levels of von Mises stress and strain energy density, and the largest value of the stress appears at the corners of the matrix near the interface. Creep dislocations penetrate preferentially into the most highly stressed matrix channels where theγ'-phase rafting is also enlarged. Meanwhile, the von Mises stress ofγmatrix andγ' precipitate increases with the increase of temperature, thus the rafting becomes easier at a higher temperature. Moreover, according to the analysis of slip systems for the Ni-based superalloy, the critical external load for bowing a dislocation through a matrix channel at 950℃is about 180 MPa, which is consistent with the related experimental results.

虚拟电厂两阶段准线型需求响应优化及收益共享-风险共担决策方法

末端分散式资源的需求响应(demand response,DR)是支撑电力系统灵活调节的重要形式,但末端资源通常规模大且单体容量小,迫切需要虚拟电厂(virtual power plant,VPP)等市场主体进行聚合代理,从而间接参与电网公司的调节服务。聚焦于准线型需求响应这一新兴的响应模式,重点研究VPP内部分散式资源的利益-风险互动协调策略,提出面向准线型DR的VPP两阶段优化及收益共享-风险共担决策方法,构建VPP与电网、内部用户互动协调新模式。首先,在准线型激励下VPP以整体收益最大化为目标,考虑柔性负荷响应积极度与新能源准确度因子,进行日前-日内两阶段DR优化;其次,在收益共享-风险共担决策方法下,VPP与柔性负荷共享准线型激励、与新能源共担不确定性风险,并以改进的Shapley法对内部柔性负荷进行利益分配。仿真结果表明,相较于传统DR,准线型DR给出全时段响应目标,更具有优越性;共享-共担决策吸引柔性负荷参与VPP调节,促使VPP与用户双赢。

基于通信负载站间迁移的配电网与5G基站日前互动运行方法

当前,将5G基站作为灵活性资源参与电网互动的研究多关注于5G基站储能资源的利用,忽视了5G基站通信负载的调节潜力。为此,提出了一种基于通信负载站间迁移的配电网运营商(DNO)与移动网络运营商(MNO)日前互动运行方法。首先,构建了DNO-MNO双层互动运行优化模型,其中,DNO是综合考虑系统网损成本与5G基站激励成本的激励策略,并以系统N-1安全运行准则为约束,以系统总运行成本最低为目标;MNO综合考虑5G基站功耗成本与电网需求响应收益,并以5G基站净运行成本最低为目标制定5G基站功率运行方案。其次,针对下层MNO 5G基站调度模型存在非凸、非线性约束难以解析求解的问题,提出了一种基于可行域迭代的算法以实现对模型的精确求解。再次,提出了基于精英遗传算法的DNO内嵌MNO双层互动模型求解算法。最后,通过算例验证了文中所提方法的有效性和实用性。

从释意理论看电影《你好,李焕英》幽默元素字幕的翻译策略

字幕翻译是观众了解非母语影视的主要手段,优秀的字幕翻译也成为海外观众更好地了解中国电影和中国文化的重要途径。字幕翻译同口译不乏相通之处,因此源于口语实践研究、倡导脱离源语言外壳束缚的释意理论,不仅指出了译者在字幕翻译过程中应了解的原则和方向,也启发译者跳出具体翻译策略的限制,根据具体情况灵活采取合适的翻译策略,对于电影字幕翻译具有实际的指导意义。华语喜剧电影中的幽默元素体现了中国浓厚鲜明的民族文化特色,是译者较难处理的部分。电影《你好,李焕英》在翻译诸如双关语、特色方言、富有时代感的流行语和富含中国文化特色的话语这些包含幽默元素的字幕时采取了替换、归化、异化、减译等不同翻译策略。